A good quality front tube which can be used for the rear tire in an emergency. We recommend carrying a "normal 3.00 X 21" front tube as a spare because it will fit in either wheel, and because it is generally smaller and lighter than a rear tube. The 3.00 X 21 front tube is the ideal spare because it can be used in either front or rear wheel to get you home. A rear tube can be used as an emergency front tube but it does not fit as well, and it is bigger and heavier to carry.
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